Detection of defect populations in superhard semiconductor boron subphosphide B₁₂P₂ through X-ray absorption spectroscopy

Abstract

Recent theoretical work 1 has shown for the first time how the experimentally observed property of "self-healing" of the superhard semiconductor boron subphosphide (B12P2) arises through a process of mediated defect recombination. Experimental verification of the proposed mechanism would require a method that can detect and distinguish between the various defect populations that can exist in B12P2. X-ray absorption near-edge spectroscopy (XANES) is such a method and in this work we present experimentally collected spectra of B12P2 samples with varying crystalline qualities. By simulating the x-ray spectroscopic signatures of potential crystallographic point defects from firstprinciples within the density functional theory framework, the presence of defect populations can be determined through spectroscopic fingerprinting. Our results find an increasing propensity for the presence of phosphorus vacancy defects in samples deposited at lower temperatures but no evidence for comparable populations of boron vacancies in all the samples that have been studied. The absence of large amounts of boron vacancies is in line with the "self-healing" property of B12P2.

Surface Chemistry and Long-Term Stability of Amorphous Zn–Sn–O Thin Films

“…Such an electronic configuration (reducing in nature, or equivalently noted as V O ′ in the Kröger–Vink notation) screens the corehole on Sn, effectively lowering the energies of available empty states. Similar observations are attributed to vacancies in various systems. , This is not seen for the Zn K edge XANES (Figure B) because the surface Zn is fully coordinated (Table ).…”

“…Similar observations are attributed to vacancies in various systems. 23,24 This is not seen for the Zn K edge XANES (Figure 1B) because the surface Zn is fully coordinated (Table 1).…”

Ductility in Crystalline Boron Subphosphide (B12P2) for Large Strain Indentation

“…Icosahedral boron phosphide, also known as boron subphosphide, exhibits novel properties such as a wide bandgap of 3.35 eV, high radiation resistance, , chemical inertness, and high hardness. − The combination of these properties makes it widely useful in radiation detection, in electronics at high radiation environments, and in radioisotope batteries. − One promising property of B 12 P 2 is the “self-healing” phenomenon in which no visible damage is observed after prolonged exposure to high energy particles . Recent QM studies revealed that the B 12 P 2 remains structurally stable in the presence of a vacancy or interstitial defect with an activation barrier for defect recombination as low as 3 meV .…”

Enhancing Catalytic Activity of MoS2 Basal Plane S-Vacancy by Co Cluster Addition

“…To better understand the adsorption configuration of S-vacancy and Co on Co/MoS 2– x on carbon foam, we performed S and Co K-edge XAS experiments. The S K-edge peak intensity of Co/MoS 2– x is weaker than that of Co/MoS 2 (Figure d), suggesting the formation of S-vacancy by the electrochemical desulfurization process . The S K-edge at 2470 eV with the shoulder at 2473 eV indicates the Mo–S bond in MoS 2 .…”

“…The S K-edge peak intensity of Co/MoS 2−x is weaker than that of Co/MoS 2 (Figure 5d), suggesting the formation of S-vacancy by the electrochemical desulfurization process. 30 The S K-edge at 2470 eV with the shoulder at 2473 eV indicates the Mo−S bond in MoS 2 . 31 In addition, the S K-edge XANES results show that the spectral shapes of Co/MoS 2 and Co/MoS 2−x are different from that of CoS 2 , indicating the absence of Co−S bonds.…”